title: The Bcl-2 homology domain 3 (BH3) mimetic ABT-737 reveals the dynamic regulation of bad, a proapoptotic protein of the Bcl-2 family, by Bcl-xL.
abstract: The proteins of the B-cell lymphoma 2 (Bcl-2) family are important regulators of apoptosis under normal and pathological conditions. Chemical compounds that block the antiapoptotic proteins of this family have been introduced, such as 4-[4-[(4'-Chloro[1,1'-biphenyl]-2-yl)methyl]-1-piperazinyl]-N-[[4-[[(1R)-3-(dimethylamino)-1-[(phenylthio)methyl]propyl]amino]-3-nitrophenyl]sulfonyl]benzamide (ABT-737), a BH3-mimetic that neutralizes Bcl-2 and Bcl-xL. In this study, we used ABT-737 to explore the dynamic regulation of Bcl-2 proteins in living cells of different origins. Using ABT-737 as well as RNA interference or the application of growth factors, we examined the impact of the functional availability of the antiapoptotic proteins Bcl-2 and Bcl-2-extra large (Bcl-xL) on the Bcl-2 network. We report that ABT-737 increases the expression of Bcl-2-associated death promoter (Bad), a proapoptotic partner of the proteins Bcl-2 and Bcl-xL. Our observations indicate that Bad overexpression induced by ABT-737 results from the control of its normally rapid protein turnover, leading to the stabilization of this protein. We demonstrate the relevance of Bad post-translational regulation by Bcl-xL to the physiological setting using RNA interference against Bcl-xL as well as the application of epidermal growth factor, a growth factor that promotes the dissociation of Bad from Bcl-xL. Our results highlight a new facet of the mode of action of the antiapoptotic proteins Bcl-2 and Bcl-xL consisting of the regulation of the stability of the protein Bad. Finally, our results shed light on the mode of action of ABT-737, currently the best characterized inhibitor of the antiapoptotic proteins of the Bcl-2 family, and bear important implications regarding its use as an anticancer drug.
authors.affiliation: Laboratoire de Biochimie, CHU Nord, 1 Place Victor Pauchet, 80054 Amiens Cedex, France.
authors.forename: Zakaria
authors.initials: Z
authors.lastname: Ezzoukhry
authors.forename: Christophe
authors.initials: C
authors.lastname: Louandre
authors.forename: Catherine
authors.initials: C
authors.lastname: François
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Saidak
authors.forename: Corinne
authors.initials: C
authors.lastname: Godin
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mazière
authors.forename: Antoine
authors.initials: A
authors.lastname: Galmiche
mesh_terms: D001713:Biphenyl Compounds / Q000494:pharmacology*; D015153:Blotting, Western; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D018716:Molecular Mimicry; D009596:Nitrophenols / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000737:chemistry / Q000378:metabolism*; D034622:RNA Interference; D013449:Sulfonamides / Q000494:pharmacology*
chemical_list: C501332:ABT-737; D001713:Biphenyl Compounds; D009596:Nitrophenols; D010879:Piperazines; D019253:Proto-Oncogene Proteins c-bcl-2; D013449:Sulfonamides